The household dishwashers described in EP 1 329 187 A2 includes dispensing systems that are adapted to store a relatively large quantity of liquid rinse aid, a fraction of this quantity then being dispensed into the washing tub during each wash cycle. DE 199 28 040 A1 also describes dispensing systems which also allow storage of liquid aftertreatment agents therein. These dispensing systems are additionally provided with a receiving compartment which is filled with detergent in the form of powder or tabs for each dishwashing cycle, and which is then emptied into the washing tub by the cycle controller during the appropriate cycle step. It is considered to be a disadvantage of these devices that the user must fill detergent into the receiving compartment for each wash cycle. Another disadvantage is that the dispensing of the detergent is performed by the user himself/herself, either based on a rough estimate of the quantity actually needed (when using powder) or without any possibility of dispensing variable amounts (when using tabs).
Storing relatively large quantities of detergent tabs or powder in the inflow region of the washing tub of a dishwasher has proved not to be practical because moisture and increases in temperature cause such agents to clump together, as a result of which they can no longer be dispensed automatically, or are caused to adhere in their reservoirs or to be impaired in their effectiveness.
Industrial cleaning and sanitizing appliances described in DE 196 43 270 A1, include a dispensing pump that supplies a particular needed quantity of an active substance from a retail container to the washing tub of the appliance. Using retail containers is not practical because such containers require additional space inside or outside the appliance to accommodate them. Moreover, an agent suitable for use in household dishwashers and intended to have the same cleaning properties as conventional powders or tabs cannot be stored in a liquid or pasty formulation. The reason for this is that the enzymes needed to degrade starch and proteins are sensitive to oxidizing agents, such as are needed in an effective bleaching system. In liquid or pasty media, these opponents cannot be separated as effectively as in detergent powders or tabs.
German Patent Document DE 103 58 969 A1 describes a dishwasher having a dispensing device in which relatively large quantities of so-called basic chemicals can be stored. The bleaching agent needed for the dishwashing process is here in the form of active chlorine gas which is generated in a microreactor. The use of chlorine gas causes the development of unpleasant odors, and when used in larger quantities, chlorine gas is even toxic.
German Patent Document DE 195 11 789 A1 describes a washing machine or dishwasher having a dispensing chamber with an adjustable volume.
German Utility Model DE 85 02 661 U1 describes a device for supplying cleaning agents in dishwashers, said device including two separate reservoirs for storing cleaning agents. This allows cleaning agent to be dispensed in the prewash cycle and in the wash cycle. The reservoirs have different capacities, the ratio of the capacities being 1:2.